432 THE COLLIERY GUARDIAN Mauch 1, 1918. determining the steam used, the steam pipe and nozzles (or a heavy casting with series of small holes, or other apparatus used on the boilers), is placed bodily in the enclosed cylinder, and coupled up in exactly the same manner as when under the firebars. The steam passes through the cylinder and coils, which are immersed in cooling water and open to the air at the end, and the steam used over a period of several hours weighed direct as condensed water. This apparatus is very simple and convenient, and gives absolutely accurate results. The figures obtained in this way by a complete scien- tific investigation of each of the 75 plants were averaged together, with the following results: — A.—Working Day Test. Type of boiler....................... Number of boilers (average) ......... Size of boilers (approximate) ....... Grate area .......................... Duration of test (hours)............. Value of coal used................... Amount of coal used ................. Analysis of coal used (B.T.U.)....... Ash.............................. Coal burnt per boiler per hour ...... Coal burnt per sq. ft. grate area per hour Total water evaporated .............. Water evaporated per boiler per hour ... Water evaporated per sq. ft. grate area per hour............................. Water evaporated per pound of coal... Equivalent evaporation from and at 212 degs. Fahr., per pound coal ... Equivalent evaporation from and at 212 degs. Fahr., per-1,000,000 B.T.U. ... Temperature of feed-wafer ........... Draught in chimney base ............. Draught in side flues ............... Temperature of flue gases in chimney base......................... ...... Percentage CO2 in flue gases (side flues of boilers)......................... Steam pressure (gauge) .............. Steam or power used as auxiliary to the production of steam................. Thermal efficiency of plant— (a) Net working efficiency of plant com- plete, after deducting steam or power used as auxiliary to the pro- duction of steam................. (b) Boilers only .................... Cost in coal to evaporate 1,000 gals, of water............................... B.—Long Check Test. Duration ............................ Price of coal used................... Amount of coal used.................. Water evaporated..................... Water evaporated per pound of coal... Cost in coal to evaporate 1,000 gals, of water .............................. “ Lancashire.” 6*14. 30 ft. x 8 ft. 6 in. 239*7 sq. ft. 8*44. 12s. per ton. 41,851 lb. 10,920. 16*5 lb. 807*6 lb. 20*7 lb. 226,630 lb. 4,3731b. 112*0 lb. 5*4 lb. 5*8 lb. 531*1 lb. 163 degs. Fahr. 0 83 in. w.g. 0’46 in. w.g. 634 degs. Fahr. 8*0 per cent. 82 lb. 1’5 per cent. 51’2 per cent. 52'0 per cent. 118’7d. 168’00 hours. 12s. 196'5 tons. 231,250 gals. 5’25 lb. 122’3d. The detailed analysis of the above average figures for the performance of 75 “typical” colliery steam boiler plants is as follows: — (1) Size of Boilers.—The average size of the boilers in use can be taken as approximately 30 ft. by 8 ft. 6 in., and, generally speaking, the size of boilers used at collieries is on the large side, as compared with other industries. Thus, boilers of 30 ft. by 9 ft. are commonly installed, and in a number of cases 30 ft. by 10 ft. (2) Grate Area.—The average length of grates in use may be said to be 6ft., although a few grates are as long as 7 ft. (3) Price of Coal Used.—This is taken as 12s., as already stated, but, of course, there are very great differences in the value of the coal used on different plants. (4) Amount of Coal Used.—The figures of 807-6 lb. of coal per boiler per hour and 20’7 lb. of coal per square foot of grate area per hour are about average, as compared with other industries, but much less than what is possible on a modern boiler plant. (5) Analysis of Coal Used. — The average figures show 10,920 b.t.u. per lb., and 16-5 per cent. ash. The figures for different plants fluctuate greatly, and the various qualities and grades of fuels in use on the 75 plants range from 8,250 b.t.u. and 25 per cent, ash to 13,500 b.t.u. and 7-5 per cent. ash. It may be remarked that the coal used on colliery boiler plants is of much better quality than is generally supposed. (6) Amount of Water Evaporated per Boiler per Hour. — As seen, the average figure obtained is 4,3731b., or 437 gals. (1 gal. = 10 lb.) per boiler per hour. This is a very low evaporation, and much below the figure that can be obtained by modern methods of steam generation. The average for all the industries of the country is about 6,0001b. Thus, a “Lanca- shire” boiler, 30 ft. by 8 ft. 6 in., with coal of the above average quality, can be made to evaporate economically 800 gals, per hour, representing nearly 100 per cent, more steam per boiler. This is thoroughly characteristic of colliery boiler plants, and in most cases 25 to 50 per cent, of the boilers in oper- ation could be shut down, and the same amount of steam generated with much greater efficiency from the remaining boilers. Very many collieries are seriously handicapped through lack of steam, and at the present time are unable to obtain extra boilers because of shortage of steel or wrought iron and labour. In nearly every case these plants could be re-organised on scientific lines to give, easily and much more efficiently, all the steam required from the exist- ing boilers. In the past, hundreds of additional boilers have been put down at collieries which were quite unnecessary, because no one had any idea what the already existing plant was doing, and what was possible with a plant run on correct lines. These remarks may be said to apply more or less to all the industries of the country, but collieries are certainly the worst in this respect. (7) Temperature of Feed Water. — As already explained in the “typical” colliery boiler plant, feed water is heated up by means of exhaust steam from the winding and other engines. It is generally supposed that by this means the feed water enters the boilers at a temperature of nearly boiling point, over 200 degs. Fahr. This, however, is not the case, the average temperature being about 163 degs. Fahr., and it is rare that the temperature exceeds an average of 180 degs. Fahr, at any particular colliery. (8) Draught in Chimney Base. — There is a great difference in the height of chimneys in use at collieries, varying from under 100 ft. to over 200 ft. for plants of average size. The highest draught observed at a chimney base was 1-70 in. water gauge, and the lowest 0-25 in. water gauge. (9) Temperature of Flue Gases in the Chimney Base.—The average found was 634 degs. Fahr., the highest being 785 degs. Fahr., and the lowest 475 degs. Fahr. (10) Percentage of CO2 in Side Flues.—The figures obtained by taking a number of days continuous records were: — 1. Very good ... ... Over 12 per cent. Per cent. Nil. 2. Good ... 10—12 ... 5'0 3. Medium 8 10 ... 29*0 4. Poor 5— 8 35*0 5. Very bad ... Under 5 ,, ... 6*0 75’0 The general average is about 8 per cent., which is better than the average for the whole country, includ- ing all industries. Thus, taking 100 typical boiler plants in about 17 different industries, the average figures were 7-5 per cent. CO2, divided as follows: — Per cent. 1. Very good ..... Over 12 per cent. ... 2 0 2. Good.......... 10—12 ,, ... 13’0 3. Medium ....... 8—10 ,, ... 30’0 4. Poor ......... 5— 8 „ ... 45*0 5. Very bad...... Under 5 ,, ... 10*0 100’0 (11) Steam Pressure.—The average found was 82 lb., the highest being 1481b., and the lowest 521b. average working. The figures in detail were as follow: — Per cent. 1. Over 160 lb. pressure Nil. 2. 120—160 ,, „ 4*0 3. 100-120 „ „ 7*0 4. 80—100 „ ,, 26*0 5. 60— 80 ,, „ 31*0 6. Below 60,, ,, 7’0 75*0 The question of the working pressure is not of much importance in connection with the economical gener- ation of steam, but, regarding the question of economy by the economical utilisation of steam, a serious loss is undoubtedly caused by the steam pressure of colliery equipment, being, generally, much too low. The average figure for all industries is about 95 lb. (12) Steam or Power Used Auxiliary to the Produc- tion of Steam.—In typical colliery boiler plants, as already seen, this auxiliary steam is used in the form of steam jets over or under the furnaces. Out of the 75 plants examined, only 20 were equipped with steam jet apparatus in this way. The amount of steam used for this purpose in the different plants varied con- siderably, the smallest amount being 1 per cent, of the production, and the largest 15 per cent., with an average figure of about 5 per cent, of the production. On the whole 75 plants, this corresponds to 1’5 per cent, of the production. Taking all industries together, it is found that steam jets may take anything from 1 to 15 per cent, of the production, the average being probably 5 to 7 per cent. (13) Net Thermal Efficiency of the Plant.—As seen, the average net thermal efficiency of the whole of the 75 typical boiler plants is only 51’2 per cent., that is to say, for every 100 lb. of coal put into the fires, only 51-2 lb. are being used to produce useful steam, the other 48-8 lb. being wasted. The best result found was 66-5 per cent., and the worst 37 per cent., the 75 plants being classified as follows: — Pei cent. Over 65 per c- nt.............. 4’0 60—65 „ 12’0 55—60 „ 180 50—55 „ 13'0 45—50 „ 21'0 Under 45 ,, 7'0 These differences are to some extent due to the quali- ties of coal used. It is, of course, much easier to get a comparatively high efficiency with good quality coal than with one of poor quality. It is not possible, within the scope of this article, to give figures for the performance of the boiler plants of each industry separately, but the experience gained in the complete scientific investigation of several hundred boiler plants in various typical industries points to the average efficiency of steam boiler plants to-day in the whole country being 62 per cent, (say, 60 to 65 per cent.), divided as follows: — Per cent. Over 80 per cent.............. 2’0 75—80 „ 7’0 70—75 „ 8’0 65-70 „ 17’0 60—65 „ 14’0 55—60 „ 29’0 50—55 „ 14’0 Under 50 .................... 9’0 100'0 In favourable circumstances, and by adopting the most modern methods, it is possible to run a “ Lanca- shire ” boiler plant at 80 per cent, efficiency, and there is certainly no reason why a typical colliery boiler plant should not be re-organised so as to run on an efficiency of 70 to 75 per cent. Taking the actual efficiency to-day, therefore, as 51’2 per cent., this means that no less than approximately 30 per cent, of the coal bill can be saved by adopting scientific methods. The directors of W. T. Henley’s Telegraph Works Com- pany Limited, 13-14, Blomfield-street, London, have pro- posed to the shareholders, subject to the consent of the Treasury, that a new company should be formed, with a capital of £200,000, to take over the motor tyre branch of the business. A NEW BRITISH OIL INDUSTRY: II * By Dr. F. Mollwo Perkin, F.I.C., F.C.S. In gas works and in coke oven practice, high tem- peratures are employed for carbonisation, because, in either case a large volume of gas of high calorific value or a hard coke for metallurgical purposes is required, with tar and sulphate of ammonia as by-products. With low-temperature carbonisation the yield of gas is comparatively small, but the maximum yield of oil is obtained, which, when refined, yields fuel oil, motor spirit, etc. Generally speaking, however, sufficient gas is produced to heat the retort settings, and carry out the carbonisation, and there may be a small surplus, which can be used for power. The products contained in high-temperature gas tar are entirely different from those found in the oil pro- duced by low-temperature carbonisation. Benzol, toluol, carbolic acid, and other products required for the manufacture of high explosives are obtained from high-temperature tar, but the quantity of creosote oil available as a fuel oil from gas works is strictly limited. Some experiments in low-temperature carbonisation were recently carried out in Lancashire in vertical retorts of the Glover-West system for the Nitrogen Products and Carbide Company, which the author supervised. In one case a special coal was retorted at a temperature of 1,411 degs. Cent., the throughput of coal in each retort being 4-2 tons in 24 hours. The temperature was then reduced to 1,194 degs., when the amount of coal passing through the retort was reduced to 2-6 tons in 24 hours—that is, almost halved. Although the amount of tar produced per ton of coal carbonised was increased, the net amount produced in 24 hours was much less, and, of course, the same applied to the net yield of gas, which was insufficient for the town requirements. In the case of steaming, considerably larger yields of tar and gas are obtained. The tar, however, con- tains very little benzol and toluol, and what there is is difficult to purify because of the admixture of aliphatic hydrocarbons. Now, in low-temperature carbonisa- tion, large quantities of oil are produced, but this oil contains no benzol or toluol; it is, therefore, useless for explosives, aniline dyes, etc. On the other hand, the lower fractions yield a light spirit, which can be employed for aeroplanes and motor-cars. The higher fractions produce fuel oil, the yield in some cases being very considerable. The following are examples of the products obtained from different coals, carbonised at low temperatures: — I.—Yorkshire Coal (Washed Smalls). 17-5 gals, of crude oil per ton of coal carbonised was obtained. Yield of sulphate of ammonia—221b. The oil yielded, on fractionation :— Oil distilling up to 150 degs. Cent. ......... 3’0 gals. Fuel oil ..................................... 11-0 gals. Paraffin wax .................................. 8-0 lb. II.—Yorkshire Cannel. Yield of crude oil—70 gals, per ton of coal carbonised. Yield of sulphate of ammonia—3-2 lb. The oil yielded, on fractionation :— Oil distilling to 170 degs. Cent................. 7-4 gals. Fuel oil ....................................... 49’3 gals. The first fraction was taken up to 170 degs., instead of 150 degs., for a special purpose. There was only a small portion of paraffin wax, which was not estimated. III.—Slack from Bituminous Yorkshire Coal. Yield of crude oil—24 gals, per ton of coal carbonised. Yield of sulphate of ammonia—221b. The oil on fractionation yielded :— Oil distilling to 170 degs. Cent.......... 2*8 gals. Fuel oil ................................. 12-0 gals. Paraffin wax .............................not determined IV.—A Scotch Cannel. Yield of crude oil—37 gals, per ton of coal. On fractionation the following yields were obtained :— Oil to 150 degs. Cent.......................... 1-0 gal. Fuel oil ..................................... 22-0 gals. V.—A Coal from Spain. Yield of crude oil—22*5 gals, per ton of coal carbonised. Yield of sulphate of ammonia—18-5 lb. The oil yielded on fractionation :— Oil up to 160 degs. Cent....................... 2-0 gals. Fuel oil .................................... 13-5 gals. After distilling off the bulk of the volatile matter from the coal, over 70 per cent, of the coal still remains in the form of valuable smokeless fuel. When the coal is burnt in an open grate with all its volatile matter in it, that is to say, before it has been retorted, the volatile matter goes off in the form of smoke and flame, and is thus largely lost. The Staffordshire blackband iron ore contains large quantities of volatile matter, and for this reason it was not feasible to smelt it without first calcining it in the wasteful manner described by Mr. Cunningham Craig. It has now been found that the volatile matter in the ore can be obtained in the form of oil by low- temperature distillation. This leaves the ore in a form in which it can be smelted to obtain iron. The actual temperatures employed for low-tempera- ture carbonisation vary from 450 to 550 degs. Cent., but different coals require different treatment; some will give up their volatile matter at a lower, and others at a higher temperature. The wear and tear of the plant is when low less than when very high tempera- tures are employed. It has for years been known that oil can be produced, and that in large quantities, from bituminous materials, and that, particularly from cannel coal, the yields are frequently very high, as examples II. and IV. show. It is now suggested that cannel coal can be satis- factorily treated in the shale oil retorts. Personally, the author doubts this, unless the retorts are consider- ably modified. On the other hand, the shale retorts are being worked to their full capacity, and therefore * From a paper read before the Institution of Petroleum Technologists on February 19.